Detective Constable Nathan Burrows, who led the investigation, said: "This was a violent incident in which the victim suffered a serious injury.

"This sentence sends a very clear message to those who carry weapons and are intent on using them: we will not tolerate violence and will do everything to secure a prosecution and to ensure justice is done."

A Ministry of Justice spokesman confirmed safety razor blades, thought to be what Shah used, are allowed in prisons for shaving purposes.